After the periderm forms and begins to differentiate, the underlying single layer of presumptive basal keratinocytes is fairly stable until the time of embryonic-fetal transition at the end of week 8 of gestation. At this point the presumptive keratinocytes divide, and give rise to daughter cells which move up to form the first intermediate layer (the layer between the basal cells and the periderm).
Note the 4-5 layers of stratified, differentiated keratinocytes overlaying a cellular dermis.
